Australian patent 482212 proposed a modular screening panel system for ore screening decks which is now widely used by the mining industry and replaced the earlier screening cloths, and large wire screening frames. The screening panels were all of the same size [eg. 300 mm] and made of reinforced polyurethane. The panels are adapted to be secured to an underlying support frame using dependent spigots which are a force fit into corresponding apertures in the support frame. The underlying support frame was designed specifically for the panels and itself was secured to the machine frame fitted as original equipment by the screening machine manufacturer.
The panels become worn and need to be replaced. The wear patterns across a screen deck are not easy to predict and not all panels in a deck need to be replaced. Hard wearing Rubber and Polyurethane panels are used to provide the optimal working life for the panels.
Patent specification WO02/074453 discloses a screening surface having two layers bonded together. There is an indication that the under layer may be of a different colour to the top surface to provide an indication that the worn panel needs replacing. This involves a more expensive process for making the panels. Another known system of wear indication is to provide closed apertures in part of the panels which open when a portion of the surface is worn. This has the disadvantage of reducing the open area of the screen and only indicates wear in the localized area of the closed aperture.
It is an object of this invention to provide a more convenient means of identifying wear without reducing open area or increasing manufacturing costs.